The black market for erectile dysfunction drugs is booming as more young men are using the medicine as a recreational party pill, Sky News has found.

Figures obtained by Sky News reveal the scale of unlicensed erectile dysfunction drug smuggling into the UK by post, ports and dealers has sharply increased over the past five years to meet demand.

The medicine regulator seized £2.5m of illicit pills in 2012-13.

By 2016 that had increased to £17.4m, bringing the total seized over the past five years to £49.4m.

Erectile dysfunction drugs now account for 90% of all captured counterfeit drugs.

Sexual psychotherapist Raymond Francis says many of his young patients use the pills as an insurance policy for performance.

He told Sky News his patients include an increasing number of young men, typically under the age of 35, invariably not in long-term relationships.

Image:Sexual psychotherapist Raymond Francis says many of his young patients use the pills as an insurance policy

He said: "I believe their dependence on Viagra for recreational reasons, if you like, is driven to some degree by the plethora of sexual imagery through pornography which is so instantly available."

Mr Francis, who works at Harley Street's Apex Practice, said he has not encountered any patients with physiological issues.

However, they became psychologically dependent on taking the drug in order to live up to the unrealistic portrayal of male sexual performance promoted in pornography.

He said: "This is one of the last few remaining taboos in modern society today, even in this day and age of openness, male sexual performance is one of the few matters in life which is really considered deeply confidential."

Image:Some are marketed as harmless sweets but unlicensed samples can contain toxic chemicals

Many young men are also trying the drug in an attempt to counter the effects of alcohol and other drugs.

The Medicines and Healthcare Products Regulatory Agency said that, despite often being marketed as harmless sweets with fruity flavours, some unlicensed samples can contain toxic chemicals such as lead and arsenic - as criminal gangs have become attracted to the lucrative market.

"When I first started doing this you'd get people flying out to India for a fortnight holiday and then coming back with a couple of suitcases, their mates designed them a little website and they were dealing it all from their spare bedroom.

Other samples seized by the regulator had well over the licenced 100mg of the active ingredient in Sildenafil.

Drug dealers are increasingly selling unlicensed pills due to the level of demand and the MHRA is running a #FakeMeds campaign to warn people against buying potentially dangerous sold by illegal online suppliers.